Sp 3 content in ta - C

Tetrahedral amorphous carbon (ta-C) films were studied with and without applying fixed pulse bias and frequency at variable pulse widths in double bent Filtered Cathodic Vacuum Arc(FCVA) system. Both from Raman and X-ray photoelectron spectroscopy(XPS) analyses it has been observed that the ratio of sp/sp is maximal at pulse width of 15 μs with fixed pulse bias 3kV and frequency 200 kHz. Increasing or decreasing pulse width from this threshold value accompanies the decreasing sp content in the film. It is also observed that with applying pulse bias width at said frequency and bias voltage G peak position was shifted to lower values and after reaching a minimum at 15μs G peak position shifted to higher wave numbers. At the 15μs pulse width, 3kV bias voltage and 200 kHz frequency we have formed ta-C films with maximum sp content. This study clearly suggests that it is possible to tune the ta-C film’s most important properties such as percentage of sp content, internal stress, hardness by applying pulse width at particular frequency and bias voltage. * Authors for correspondence: [email protected] or [email protected] Novelty of this work: AC C EP TE D M AN U SC R IP T ACCEPTED MANUSCRIPT The most important properties of ta-C film such as hardness, transparency, chemical inertness depend on its sp3 content. In the filed of DLC research major focus is to grow higher sp3 content films with reduced residual stress. The novelty and main important work in this paper is to grow maximum sp3 content ta-C film with possible reduced residual stress. In this paper we aim to highlight the effect of pulse width on the ta-C growth process through extensive XPS and Raman analyses. We have found that to retain high content sp3 in the ta-C film one must tune pulse width at particular frequency and bias voltage very carefully and accurately. Deviation from the threshold pulse width at particular frequency and bias voltage not only causes higher sp2 content in the film but it may also increase residual stress of the film. To elucidate these types of phenomena is very important in terms of technological implication of ta-C film.